1. Field of the Invention
The present invention generally relates to a method and apparatus for ciphering data in a wireless communication system, and more particularly, to a method and apparatus for ciphering data, which transmits ciphered data directly to a Radio Frequency (RF) communication unit, which operates at the physical layer, without transmitting the data to a memory, using a protocol processing unit which can simultaneously perform ciphering and transmission data processing.
2. Description of the Related Art
In W-CDMA (Wideband Code Division Multiple Access) and HSPA (High Speed Packet Access) of 3GPP (3rd Generation Partnership Project), the ciphering process of security level 1 is stipulated to process in each protocol and layer of RRC (Radio Resource Control)/RLC (Radio Link Control)/MAC (Media Access Control). Here, security level 1 refers to a security level in a layer, where a terminal and a base station directly transmit and receive data.
With respect to a layer where ciphering is processed, in the RRC layer, a control message is transmitted, and in the RLC/MAC layer, user data is transmitted. Particularly, the method of transmitting data when transmitting user data is classified into UM (Unacknowledge Mode), AM (Acknowledge mode) and TM (Transparent Mode), and UM/AM mode data are ciphered in RLC layer and TM mode data are ciphered in MAC sub-layer.
Further, the existing method of implementing ciphering can be classified into a method of using software and a method of using hardware. When ciphering is implemented using software, the controller of a transceiver (a terminal or a base station) should read and cipher data stored in a memory, and then store the data in the memory again. Such a method can be easily implemented in case the data transmission rate does not have to be as high as in control message processing, but the processing time can be delayed if high data transmission rate is needed.
Additionally, if the case ciphering is implemented in hardware, if the controller of a transceiver transmits information for ciphering data stored in a memory to a cipher hardware, the cipher hardware reads data from the memory, ciphers the data, and stores the ciphered data in the memory again. Such a method is a general ciphering method that is used to process data with a high transmission rate.
However, in order to transmit data, a MAC packet needs to be generated by adding a MAC header to the ciphered data. To this end, the cipher hardware should access a memory again and read ciphered data. Thus, the number of times of memory accessed by the cipher hardware increases, thereby finally delaying the data processing.
Hence, there is a need for a method of ciphering data, which can quickly perform data ciphering and transmission processing.